Terminating 1 procedure in a List

[David Hairston]

I am designing an experiment in which it will be necessary to "permanently" terminate (i.e., no more sampling) individual Procedures within the same List as some criterion is met.  For example, assume 4 procedures, A, B, C, and D.  When X incorrect responses occur during Proc A, B-D continue, until the same occurs for each independently.  Any suggestions as to how to do this?
 
I have attemped using script to use the SetWeight method on the Factor object to reset the weight of the current procedure to 0, effectively removing it from the list.  This is done in an Inline at the end of each procedure, if that matters.  This *seems* to work, except that 1.) it takes 1 more sample before dropping out, and more crucially 2.) when all procedure weights are set to 0 (i.e., after last one hits criterion) E-Prime crashes and I get a lovely Windows error saying that an illegal operation has been performed....
...I'm guessing this is because its going back for another sample and discovers it can't because there are none.
Anybody have a suggestion on how to do this, or why it is looking to take 1 more sample after (theoretically) the weight has been set to 0?
 
Thanks,
Dave